Telegraph-insulator



UNITED STATES PATENT OFFICE.

JACOB D. PUTNAM, OF SOUTH LYNDEBOROUGH, NE\V HAMPSHIRE.

TELEGRAPH-INSULATOR.

SPECIFICATION forming part of Letters Patent No. 324,957, dated August 25, 1885.

(No model.)

To all whom, it may concern:

Be it known that I, JACOB .D. PUTNAM, of South Lyndeborough, in the county of Hillsborough and State of New Hampshire, have invented certain new and useful Improvements in Telegraph-Insulators; and I do hereby declare that the following is a full, clear,and exact description of the invention, which will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to letters of reference marked thereon, which form a part of this specification.

My invention has for its object the furnishing of an insulator which combines great strength to withstand blows or shocks, facility of being applied to telegraph poles or bars, a provision for shedding water and snow, and serving also to keep the current on the line, besides other advantages, such as dispensing with the use of pins or pegs which are usually employed for securing the insulator to place, the whole being a single solid piece, and with the least possible liability to be broken, either during its manufacture,transportation, or handling, and at the same time simple and economical.

I construct my insulator,preferably,of glass or porcelain, though it may be made of wood or other suitable non-condueting material.

Figures 1 and 2 are respectively an elevation and a vertical section of one form of my improved insulator; Figs. 3 and 4, similar views of another form; Fig. 5, an elevation having the threaded end both at top and bottom, instead of at the bottom only; and Fig. 6, a bottom view of Figs. 1, 2, 3, and 5.

The insulator A is made in a single piece, its lower part, I), being very stout and strong, and preferably entirely solid and without any interior thread, for the reason that it is not to be screwed or fastened upon any pin or peg; hut,on the contrary,it is made with a sunken thread on its exterior, whereby it may easily be inserted and screwed into any appropriate hole made for it either in the top of a telegraphpole or in the bars or cross-beams usually attached to these poles, or in any other insulatorsupporter. The average diameter of this por tion I) may be, as shown, about equal to the height of the threaded portion, and this threaded portion tapers slightly toward its diately above the sunken threaded portion I extends a short distance upward, as shown, and then curves upward and widens outward to an extent equal, or nearly so, to double the diameter of the shank b, thus affording a wide flange, d, which, when the insulator is screwed to place for use, is not only somelittle distance above the opening in the pole or bar into which the screw part is inserted, but also projects over and beyond it in every direction.

This feature has several advantages. It answers the purpose of what is usually known as thepetticoat. It prevents the current of electricityfrom jumping the wire. Its short distance above the hole in which the screw is inserted is such as to prevent water being drawn in and retained by capillary attraction between the flange and the wood of the pole or bar, thus saving the latter from rot and decay at what would otherwise be its most vulnerable point, or that mostliable to injury under exposure to the weather. It also, by reason of its wide flare, sheds the rain, snow, and

hail off from this screw-hole, and in this way also protecting the wood from wet and decay, the upper side of this flange being preferably inclined outward, as shown in Figs. 3 and 4, thus serving better to shoot or drive off any rain or hail falling on it, though in some cases it may be made without this upper incline or roof, as shown in Figs. 1 and 2.

The broad solid character of the threaded part b and of its end or base 9, which is nearly or quite equal to that of the head 0, the strength and solidity of the flange, which is thick at its outermost edge and gradually still thicker inward from such edge, and the shortness of the head, and all being in one compact piece, render this insulator extremely strong and capable of sustaining a great weight, and

the exceedingly firm hold it takes upon the pole or wood, into which it is screwed but a short distance, of, say, one and a quarter inch, especially in view of the taper and the sunken thread,whieh permit avery tight union of the insulator with the wood, renders the de vice a very valuable one independently of its great simplicity and chcapness.

Each of my insulators has of course the usual groove, f, for receiving the wire of a telegraph or telephone line.

When the base 9 of the insulator rests on the bottom of the hole in which it is inserted, its support is firm, even independently of and in addition to that derived from its sunken and close thread.

The small cavity shown in the bottom of Fig. l is not for the purpose of receiving a pin or of performing any function stated above. It is not an essential. It sometimes facilitates the manufacturing of the article to make them in that way, still leaving, however, all the requisite strength in the threaded part.

\Vhile I have named glass or porcelain as appropriate materials, yet it will be understood that the solidity and strength of its construction is such as to admit of its beingmade of any plastic or other suitable material having but small conductivity, and-that the charactor of the threaded part makes the bearing (when the insulator is in use) uniform, even, and equal for the whole length of the screw.

I sometimes make the device with two screws and two flanges, as shown in Fig. 5. This affords the additional advantage that if by accident either of the threaded ends should become broken the insulator may be inverted and the other end used to fasten it to place, thus giving the device a double value, and making one do the duty of two, and with but a trifling addition to its material or cost.

It will be observed that there is no weak point in the insulator; that I have no gimletpointed or delicate screw, no metallic auxiliary screw, no out, slit, or opening of any sort in the top or head, either for receiving or permitting the deposit or retention in it of dirt, Water, or snow; that the insulator is simply and cheaply made, and of any size or form desired, so long as it embodies the essential characteristics, described, of myinvention; that all wooden or other pins or pegs usually employed to enter athreaded and weakening cavity in the bottom of theinsulator are dispensed with, and consequently all liability to burst open such part of the insulator in the act of screwing it to place; that in screwing mine to place all pressure is from circumference to cenler of the threaded part,instead of from center to circumference of an already-weakened internally-threaded shell,and that the maximum of strength is attained with the minimum of cost and facility of manufacture, the whole device being made at a single operation. To apply it, nothing is needed but to bore a hole of proper size to receive the screw part.

I claim- 1. The insulator-knob made as shown and described, having the broad-bottomed part I), provided with a sunken thread or spiral groove, and with the short unthreaded part 0 above such threaded portion, and having the broad flange or water-shed (Z projecting abruptly beyond such part c, and to an extent nearly equal to double the diameter of the part b, and having above such flange the annular groove surmounted by a head of materially less diameter than that of the water-shed.

2. The reversible insulator made with the two solid broadbottomed tapering parts I), each having an external sunken thread, as shown and described.

J AGOB D. PUTN AM.

Vitncsses:

It. M. MooRE, A. O. BARKER. 

